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The three Laves phases are intermetallic compounds composed of CN12 and CN16 polyhedra with AB stoichiometry, commonly seen in binary metal systems like MgZn. Due to the small solubility of AB structures, Laves phases are almost line compounds, though sometimes they can have a wide homogeneity region. | 0 | Metallurgy |
As long ago as 1890, Hiorns observed as follows:
:"Noble Metals. Gold, Platinum, Silver, and a few rare metals. The members of this class have little or no tendency to unite with oxygen in the free state, and when placed in water at a red heat do not alter its composition. The oxides are readily decomposed by heat in consequence of the feeble affinity between the metal and oxygen."
Smith, writing in 1946, continued the theme:
:"There is no sharp dividing line [between noble metals and base metals] but perhaps the best definition of a noble metal is a metal whose oxide is easily decomposed at a temperature below a red heat."
:"It follows from this that noble metals...have little attraction for oxygen and are consequently not oxidised or discoloured at moderate temperatures."
Such nobility is mainly associated with the relatively high electronegativity values of the noble metals, resulting in only weakly polar covalent bonding with oxygen. The table lists the melting points of the oxides of the noble metals, and for some of those of the non-noble metals, for the elements in their most stable oxidation states. | 0 | Metallurgy |
The members of the LDLR family are characterized by distinct functional domains present in characteristic numbers. These modules are:
* LDL receptor type A (LA) repeats of 40 residues each, displaying a triple-disulfide-bond-stabilized negatively charged surface; certain head-to-tail combinations of these repeats are believed to specify ligand interactions;
* LDL receptor type B repeats, also known as EGF precursor homology regions, containing EGF-like repeats and YWTD beta propeller domains;
* a transmembrane domain, and
* the cytoplasmic region with (a) signal(s) for receptor internalization via coated pits, containing the consensus tetrapeptide Asn-Pro-Xaa-Tyr (NPxY). This cytoplasmic tail controls both endocytosis and signaling by interacting with the phosphotyrosine binding (PTB) domain-containing proteins.
In addition to these domains which can be found in all receptors of the gene family, LDL receptor and certain isoforms of ApoER2 and VLDLR contain a short region which can undergo O-linked glycosylation, known as O-linked sugar domain. ApoER2 moreover, can harbour a cleavage site for the protease furin between type A and type B repeats which enables production of a soluble receptor fragment by furin-mediated processing. | 1 | Gene expression + Signal Transduction |
The traditional technique of titanium production is via the Kroll process which involves chlorination of TiO ore in the presence of carbon and reacting the resulting TiCl with magnesium to produce titanium sponge. These processes take place at temperatures as high as 1040 °C. The sponge particle range in size from 45 to 180 μm, with particles ~150 μm termed sponge fines. These fines are irregularly shaped and porous with a sponge-like morphology. The fines are then blended with alloy additions; cold compacted into a green compact at up to 415 MPa then vacuum sintered at 1260 °C to produce a 99.5% dense component. Hot isostatic pressing (HIP) can further increase the density of these parts and produce components more economically than cast or wrought parts, but the porosity present in the material degrades fatigue and fracture properties. The BE approach has been used to produce valves for the Toyota Altezza, golf club heads and softball bats. More recently, close to 100% dense Ti Grade 5 parts has been achieved using a hydrided powder along with 60:40 Al:V master alloy. The mechanical properties compare well with those exhibited by cast-and-wrought products. A cost estimate of less than $3.00 for a 0.320 g automotive connection link has been made. | 0 | Metallurgy |
Acids with a pH of less than 2 or alkalis with a pH above 12 are capable of causing the most extensive injuries in ingestions. Alkalis damage tissue by saponifying fats, leading to liquefaction necrosis which allows the alkalis to reach deeper tissues. Acids denature proteins via coagulation necrosis, this type of necrosis is thought to prevent the acid from reaching deeper tissues. Clinically, the pH, concentration, volume of ingested substance in addition to the duration of time in contact with tissue as well as percentage of body surface area involved determine the severity of the injury. | 0 | Metallurgy |
CKLF-like MARVEL transmembrane domain-containing 5 (CMTM5), previously termed chemokine-like factor superfamily 5 (i.e. CKLFSF5), designates any one of the six protein isoforms (termed CMTM5-v1 to CMTM5-v6) encoded by six different alternative splices of its gene, CMTM5; CMTM5-v1 is the most studied of these isoforms. The CMTM5 gene is located in band 11.2 on the long (i.e. "q") arm of chromosome 14.
The CMTM5 isoforms are members of the CKLF-like MARVEL transmembrane domain-containing family (CMTM). This family consists of 9 proteins although most of them are known to have one or more isoforms. These proteins are: chemokine-like factor (i.e. CLF, the founding member of the family) and CEF-like marvel transmembrane domain-containing 1 through 8 (i.e. CMTM1 through CMTM8). All of these proteins as well as the genes responsible for their production (i.e. CKLF and CMTM1 to CMTM8, respectively) have similar structures but vary in their apparent physiological and pathological functions. Preliminary studies suggest that CMTM5-v1 (which cells commonly secrete to the extracellular spaces such as the blood) or an unspecified CMTM5 isoform has various functions including involvements in regulating the autoimmune system, the development of numerous types of cancers, and the cardiovascular system. | 1 | Gene expression + Signal Transduction |
All-trans-retinal is also an essential component of microbial opsins such as bacteriorhodopsin, channelrhodopsin, and halorhodopsin, which are important in bacterial and archaeal anoxygenic photosynthesis. In these molecules, light causes the all-trans-retinal to become 13-cis retinal, which then cycles back to all-trans-retinal in the dark state. These proteins are not evolutionarily related to animal opsins and are not GPCRs; the fact that they both use retinal is a result of convergent evolution. | 1 | Gene expression + Signal Transduction |
Matte is a term used in the field of pyrometallurgy given to the molten metal sulfide phases typically formed during smelting of copper, nickel, and other base metals. Typically, a matte is the phase in which the principal metal being extracted is recovered prior to a final reduction process (usually converting) to produce blister copper. The matte may also collect some valuable minor constituents such as noble metals, minor base metals, selenium or tellurium. Mattes may also be used to collect impurities from a metal phase, such as in the case of antimony smelting. Molten mattes are insoluble in both slag and metal phases. This insolubility, combined with differences in specific gravities between mattes, slags, and metals, allows for separation of the molten phases. | 0 | Metallurgy |
A common quantity used to describe the collection efficiency of a froth flotation process is flotation recovery (). This quantity incorporates the probabilities of collision and attachment of particles to gas flotation bubbles.
where:
* , which is the product of the probability of the particle being collected () and the number of possible particle collisions ()
* is particle diameter
* is bubble diameter
* is a specified height within the flotation which the recovery was calculated
* is the particle concentration
The following are several additional mathematical methods often used to evaluate the effectiveness of froth flotation processes. These equations are more simple than the calculation for flotation recovery, as they are based solely on the amounts of inputs and outputs of the processes.
For the following equations:
* is the weight percent of feed
* is the weight percent concentrate
* is the weight percent of tailings
* , , and are the metallurgical assays of the concentrate, tailings, and feed, respectively
Ratio of feed weight to concentrate weight (unitless)
Percent of metal recovered () in wt%
Percent of metal lost () in wt%
Percent of weight recovered in wt%
This can be calculated using weights and assays, as . Or, since , the percent of metal recovered () can be calculated from assays alone using .
Percent of metal lost is the opposite of the percent of metal recovered, and represents the material lost to the tailings. | 0 | Metallurgy |
T-complex protein Ring Complex (TRiC), otherwise known as Chaperonin Containing TCP-1 (CCT), is a multiprotein complex and the chaperonin of eukaryotic cells. Like the bacterial GroEL, the TRiC complex aids in the folding of ~10% of the proteome, and actin and tubulin are some of its best known substrates. TRiC is an example of a biological machine that folds substrates within the central cavity of its barrel-like assembly using the energy from ATP hydrolysis. | 1 | Gene expression + Signal Transduction |
The tetratricopeptide repeat domain provides the concave surface necessitated for SIP recognition. RopB-CTD houses 5 stacked TPR motifs, each having sets of paired antiparallel helices that aid in the formation of a concave inner pathway and a convex exterior. The base of the recognition site is constructed by α6 and α8 helices [See Also: alpha helix], while the supporting walls are constructed from helices α2, and α12. The exterior portion of the recognition site is flanked by asparagines N152 and N192 thus providing a ridge of support for the peptide-protein complex. | 1 | Gene expression + Signal Transduction |
STAT1 loss of function, therefore STAT1 deficiency can have many variants. There are two main genetic impairments that can cause response to interferons type I and III. First there can be autosomal recessive partial or even complete deficiency of STAT1. That causes intracellular bacterial diseases or viral infections and impaired IFN a, b, g and IL27 responses are diagnosed. In partial form there can also be found high levels of IFNg in blood serum. When tested from whole blood, monocytes do not respond to BCG and IFNg doses with IL-12 production. In complete recessive form there is a very low response to anti-viral and antimycotical medication. Second, partial STAT1 deficiency can also be an autosomal dominant mutation; phenotypically causing impaired IFNg responses and causing patients to suffer with selective intracellular bacterial diseases (MSMD).
In knock-out mice prepared in the 90s, a low amount of CD4 and CD25 regulatory T-cells and almost no IFNa, b and g response was discovered, which lead to parasital, viral and bacterial infections. The very first reported case of STAT1 deficiency in human was an autosomal dominant mutation and patients were showing propensity to mycobacterial infections. Another case reported was about an autosomal recessive form. 2 related patients had a homozygous missense STAT1 mutation which caused impaired splicing, therefore a defect in mature protein. Patients had partially damaged response to both IFNa and IFNg. Scientists now claim that recessive STAT1 deficiency is a new form of primary immunodeficiency and whenever a patient suffers sudden, severe and unexpected bacterial and viral infections, should be considered as potentially STAT1 deficient.
Interferons induce the formation of two transcriptional activators: gamma-activating factor (GAF) and interferon-stimulated gamma factor 3 (ISGF3). A natural heterozygous germline STAT1 mutation associated with susceptibility to mycobacterial but not viral disease was found in two unrelated patients with unexplained mycobacterial disease. This mutation caused a loss of GAF and ISGF3 activation but was dominant for one cellular phenotype and recessive for the other. It impaired the nuclear accumulation of GAF but not of ISGF3 in cells stimulated by interferons, implying that the antimycobacterial but not the antiviral effects of human interferons are mediated by GAF. More recently, two patients have been identified with homozygous STAT-1 mutations who developed both post–BCG vaccination disseminated disease and lethal viral infections. The mutations in these patients caused a complete lack of STAT-1 and resulted in a lack of formation of both GAF and ISGF3. | 1 | Gene expression + Signal Transduction |
The types of RNAs transcribed from RNA polymerase III include:
*Transfer RNAs
*5S ribosomal RNA
*U6 spliceosomal RNA
*RNase P and RNase MRP RNA
*7SL RNA (the RNA component of the signal recognition particle)
*Vault RNAs
*Y RNA
*SINEs (short interspersed repetitive elements)
*7SK RNA
*Several microRNAs
*Several small nucleolar RNAs
*Several gene regulatory antisense RNAs | 1 | Gene expression + Signal Transduction |
In addition to the specialisation factories have for the type of RNA polymerase they contain, there is a further level of specialisation present. There are some factories that only transcribe a certain set of related genes, this further strengthens the concept that the main function of a transcription factory is for transcriptional efficiency. | 1 | Gene expression + Signal Transduction |
Sulfur has long been known to contribute to damage. This is true for many materials such as metal corrosion, or concrete degradation. In King Lear, Shakespeare says: | 0 | Metallurgy |
Throughout his life, Tom was a committed Christian and contributed to wider society, helping to form over thirty Young Men's Christian Associations across the North of England. He was also Captain of his local Fire Brigade. One of his lasting legacies is the Cleveland Institution of Engineers. The Institution is one of the oldest such engineering bodies in the world. Tom hosted the inaugural meeting at his home on Church Road in Stockton and was the first secretary of the organisation. There were 12 members at that first meeting, but by the time of his death (when he was president) the ranks had grown to over 460. | 0 | Metallurgy |
While the exact epistasis of Imd pathway signalling components is continually scrutinized, the mechanistic order of many key components of the pathway is well-established. The following sections discuss Imd signalling as it is found in Drosophila melanogaster, where it is exceptionally well-characterized. Imd signalling is activated by a series of steps from recognition of a bacterial substance (e.g. peptidoglycan) to the transmission of that signal leading to activation of the NF-κB transcription factor Relish. Activated Relish then forms dimers that move into the nucleus and bind to DNA leading to the transcription of antimicrobial peptides and other effectors. | 1 | Gene expression + Signal Transduction |
This piece is the larger part of the fragment broken during Bahadur Shah's reign. Henry Cousens (1902–03) measured its length as . Klaus Roessler (1995) found it to be long. It has a square cross-section. Roessler estimated its weight at .
In 1598, the Mughal emperor Akbars visit to Dhar was recorded on the pillar in form of a Persian language inscription. This piece also has some names and letters in Devanagari script. The names end in word Soni' ("goldsmith"), and seem to have been engraved while the original pillar was still intact. There are some other symbols and Persian characters scratched on the surface.
The autobiography of Akbars son Jahangir mentions that he saw this piece lying on ground in Dhar. He ordered it to be taken to Agra, intending to use it as a lamp post in the courtyard of Akbars tomb. It appears that Jahangir's orders were never carried out.
Until 1980, this piece lay in a sloping position against a masonry terrace. The local kids used it as a slide, because of which a large part of its surface gained a polished appearance. | 0 | Metallurgy |
The crushed ore is irrigated with a dilute alkaline cyanide solution. The solution containing the dissolved precious metals in a pregnant solution continues percolating through the crushed ore until it reaches the liner at the bottom of the heap where it drains into a storage (pregnant solution) pond. After separating the precious metals from the pregnant solution, the dilute cyanide solution (now called "barren solution") is normally re-used in the heap-leach-process or occasionally sent to an industrial water treatment facility where the residual cyanide is treated and residual metals are removed. In very high rainfall areas, such as the tropics, in some cases there is surplus water that is then discharged to the environment, after treatment, posing possible water pollution if treatment is not properly carried out.
The production of one gold ring through this method, can generate 20 tons of waste material.
During the extraction phase, the gold ions form complex ions with the cyanide:
Recuperation of the gold is readily achieved with a redox-reaction:
The most common methods to remove the gold from solution are either using activated carbon to selectively absorb it, or the Merrill-Crowe process where zinc powder is added to cause a precipitation of gold and zinc. The fine product can be either doré (gold-silver bars) or zinc-gold sludge that is then refined elsewhere. | 0 | Metallurgy |
The alternative yeast nuclear code (translation table 12) is a genetic code found in certain yeasts. However, other yeast, including Saccharomyces cerevisiae, Candida azyma, Candida diversa, Candida magnoliae, Candida rugopelliculosa, Yarrowia lipolytica, and Zygoascus hellenicus, definitely use the standard (nuclear) code. | 1 | Gene expression + Signal Transduction |
Professor Harald Christian Pederson founded the A/S Ila and Lilleby smelteverk melting facilities in the 1920s. He worked with a chemical process which later has been called the Pederson-2 process. It consists of melting ironmalm which gives ferrosilicon as a by-product. | 0 | Metallurgy |
Sustainable materials are key elements of green buildings. Some benefits of sustainable materials include durability, long life, recyclability, and energy and thermal efficiency. Copper ranks highly in all of these categories.
Copper is one of natures most efficient thermal and electrical conductors, which helps to conserve energy. Because of its high thermal conductivity, it is used extensively in building heating systems, direct exchange heat pumps, and solar power and hot water equipment. Its high electrical conductivity increases the efficiency of lighting, electrical motors, fans, and appliances, making a buildings operation more cost effective with less energy and environmental impact.
Because copper has a better thermal conductivity rating than usual façade and roofing materials, it is well-suited to solar thermal façade systems. The first commercial application of a fully integrated solar thermal copper façade system was installed at the Pori Public Swimming Complex in Finland. The installation is an urban example of sustainability and carbon emissions reduction. The solar façade works in conjunction with roof collectors and is supplemented by roof-mounted photovoltaics that provide 120,000 kWh of heat, an amount of energy equivalent to that used annually by six average family houses in cold-climate Finland.
One standard in the United States Green Building Council (USGBC)'s Leadership in Energy and Environmental Design rating system (LEED) requires that newly constructed buildings include materials containing pre- and post-consumer recycled content. Most copper products used in construction (except electrical materials that require highly refined virgin copper) contain a large percentage of recycled content. See: Copper in architecture#Recycling. | 0 | Metallurgy |
Translation promotes transcription elongation and regulates transcription termination. Functional coupling between transcription and translation is caused by direct physical interactions between the ribosome and RNA polymerase ("expressome complex"), ribosome-dependent changes to nascent mRNA secondary structure which affect RNA polymerase activity (e.g. "attenuation"), and ribosome-dependent changes to nascent mRNA availability to transcription termination factor Rho ("polarity"). | 1 | Gene expression + Signal Transduction |
Spliceosomal splicing and self-splicing involve a two-step biochemical process. Both steps involve transesterification reactions that occur between RNA nucleotides. tRNA splicing, however, is an exception and does not occur by transesterification.
Spliceosomal and self-splicing transesterification reactions occur via two sequential transesterification reactions. First, the 2OH of a specific branchpoint nucleotide within the intron, defined during spliceosome assembly, performs a nucleophilic attack on the first nucleotide of the intron at the 5 splice site, forming the lariat intermediate. Second, the 3OH of the released 5 exon then performs a nucleophilic attack at the first nucleotide following the last nucleotide of the intron at the 3' splice site, thus joining the exons and releasing the intron lariat. | 1 | Gene expression + Signal Transduction |
CCL7 is a multipotent chemokine involved in anti-bacterial, anti-viral and anti-fungal immune responses. For example, CCL7-mediated stimulation of CCR2 chemokine receptors on monocytes is participating in the elimination of Listeria monocytogenes infections by the recruitment of monocytes and TNF/iNOS-producing dendritic cells (TipDCs). Next, the role of the CCL7 was also observed in the mouse infected by West Nile Virus. The genetically deficient mice in CCL7 have increased mortality because of decrease in monocytes and neutrophils. Early induction of CCL7 downstream of TLR9 signaling also promotes the development of robust immunity to cryptococcal infections.
Diseases associated with CCL7 dysregulation are observed. For example, an abnormal increase of CCL7 worsens many disorders, like HIV or lesional psoriasis. Furthermore, CCL7 is implicated in various immunological diseases, as ulcerative colitis, multiple sclerosis or nonatopic and atopic asthma.
It seems, that the expression of CCL7 can activate an antitumor immune response. | 1 | Gene expression + Signal Transduction |
Ultra-high-carbon steel has approximately 1.25–2.0% carbon content. Steels that can be tempered to great hardness. Used for special purposes such as (non-industrial-purpose) knives, axles, and punches. Most steels with more than 2.5% carbon content are made using powder metallurgy. | 0 | Metallurgy |
Calamine brass is brass produced by a particular alloying technique using the zinc ore calamine directly, rather than first refining it to metallic zinc. Direct zinc smelting appears to have been unknown in Europe until the mid-18th century, even though the alloyed calamine brass was in use for centuries, and metallic zinc was produced directly via reducing-atmosphere smelting in India and China from the 12th century CE onwards.
Brass is an alloy of copper and zinc and, when it was first developed, methods for producing metallic zinc were unknown. Metallurgists wishing to produce brass thus used calamine (actually a mixture of the virtually indistinguishable zinc ores smithsonite and hemimorphite) as the zinc component of brass. The resulting brasses, produced by heating a mixture of copper and calamine to a high temperature for several hours (allowing zinc vapor to distill from the ores and permeate the metallic copper), contained a significant amount of slag material resulting from the non-zinc components of calamine. The use of ore rather than metallic zinc also made it difficult to accurately produce the desired final proportion of copper to zinc. This process is known as cementation.
Calamine brass was produced using proportions of two-sevenths fine copper, four-sevenths calamine, and one-seventh shruff (old plate brass). Calamine brass was the first type of brass produced, probably starting during the 1st millennium BC, and was not replaced in Europe by other brass manufactures until the 18th century. It is likely that Indian brass manufacturers had developed more advanced techniques some centuries earlier.
The area around La Calamine, now Kelmis, in Belgium, was the source of much of the medieval brass of northern Europe. Brass production was introduced to England in 1587 when several members of the Company of Mineral and Battery Works obtained a licence from the company (within whose monopoly it was) to build a brass works at Isleworth. However a decade later the company obstructed the owners from mining calamine. A plaque at Tintern Abbey claims that the well-known brassworks at this site began in 1568.
New brass works were built by a German immigrant in 1649 at Esher, probably using Swedish copper. After the passing of the Mines Royal Act in 1689, further works were built near Bristol, where brass production became a major industry in the 18th century. Later brass production sites in England included Cheadle and Birmingham.
Calamine brass was slowly phased out as zinc smelting techniques were developed in Europe, which produced metallic zinc more suitable for brass production than calamine. However, the conversion away from calamine brass manufacture was slow; a British patent was awarded to William Champion in 1738, but the alloying of metallic zinc and copper to produce brass was not patented until 1781 (by James Emerson), and calamine brass mills persisted in South Wales until as late as 1858. The slow diffusion of this technology was probably the result of economic factors. | 0 | Metallurgy |
Characterization of microstructures has also been performed using x-ray diffraction (XRD) techniques for many years. XRD can be used to determine the percentages of various phases present in a specimen if they have different crystal structures. For example, the amount of retained austenite in a hardened steel is best measured using XRD (ASTM E 975). If a particular phase can be chemically extracted from a bulk specimen, it can be identified using XRD based on the crystal structure and lattice dimensions. This work can be complemented by EDS and/or WDS analysis where the chemical composition is quantified. But EDS and WDS are difficult to apply to particles less than 2-3 micrometers in diameter. For smaller particles, diffraction techniques can be performed using the TEM for identification and EDS can be performed on small particles if they are extracted from the matrix using replication methods to avoid detection of the matrix along with the precipitate. | 0 | Metallurgy |
It is not certain when the pillar was moved to Delhi from its original location. Alexander Cunningham attributed the relocation to the Tomara king Anangpal, based on the short pillar inscription ascribed to this king. Pasanaha Chariu, an 1132 CE Jain Apabhramsha text composed by Vibudh Shridhar, states that "the weight of his pillar caused the Lord of the Snakes to tremble". The identification of this pillar with the iron pillar lends support to the theory that the pillar was already in Delhi during Anangpal's reign.
Another theory is that the relocation happened during the Muslim rule in Delhi. Some scholars have assumed that it happened around 1200 CE, when Qutb al-Din Aibak commenced the construction of the Qutb complex as a general of Muhammad of Ghor.
Finbarr Barry Flood (2009) theorizes that it was Qutb al-Din's successor Iltutmish (r. 1210–1236 CE), who moved the pillar to Delhi. According to this theory, the pillar was originally erected in Vidisha and that the pillar was moved to the Qutb complex, by Iltutmish when he attacked and sacked Vidisha in the thirteenth century. | 0 | Metallurgy |
Unlike DNA editing, which is permanent, the effects of RNA editing − including potential off-target mutations in RNA − are transient and are not inherited. RNA editing is therefore considered to be less risky. Furthermore, it may only require a guide RNA by using the ADAR protein already found in humans and many other eukaryotes' cells instead of needing to introduce a foreign protein into the body. | 1 | Gene expression + Signal Transduction |
Concern about the copper supply is not new. In 1924 geologist and copper-mining expert Ira Joralemon warned:
:... the age of electricity and of copper will be short. At the intense rate of production that must come, the copper supply of the world will last hardly a score of years. ... Our civilization based on electrical power will dwindle and die. | 0 | Metallurgy |
In metal base-pairing, the Watson-Crick hydrogen bonds are replaced by the interaction between a metal ion with nucleosides acting as ligands. The possible geometries of the metal that would allow for duplex formation with two bidentate nucleosides around a central metal atom are tetrahedral, dodecahedral, and square planar. Metal-complexing with DNA can occur by the formation of non-canonical base pairs from natural nucleobases with participation by metal ions and also by the exchanging the hydrogen atoms that are part of the Watson-Crick base pairing by metal ions. Introduction of metal ions into a DNA duplex has shown to have potential magnetic or conducting properties, as well as increased stability.
Metal complexing has been shown to occur between natural nucleobases. A well-documented example is the formation of T-Hg-T, which involves two deprotonated thymine nucleobases that are brought together by Hg and forms a connected metal-base pair. This motif does not accommodate stacked Hg in a duplex due to an intrastrand hairpin formation process that is favored over duplex formation. Two thymines across from each other do not form a Watson-Crick base pair in a duplex; this is an example where a Watson-Crick basepair mismatch is stabilized by the formation of the metal-base pair. Another example of a metal complexing to natural nucleobases is the formation of A-Zn-T and G-Zn-C at high pH; Co and Ni also form these complexes. These are Watson-Crick base pairs where the divalent cation in coordinated to the nucleobases. The exact binding is debated.
A large variety of artificial nucleobases have been developed for use as metal base pairs. These modified nucleobases exhibit tunable electronic properties, sizes, and binding affinities that can be optimized for a specific metal. For example, a nucleoside modified with a pyridine-2,6-dicarboxylate has shown to bind tightly to Cu, whereas other divalent ions are only loosely bound. The tridentate character contributes to this selectivity. The fourth coordination site on the copper is saturated by an oppositely arranged pyridine nucleobase. The asymmetric metal base pairing system is orthogonal to the Watson-Crick base pairs. Another example of an artificial nucleobase is that with hydroxypyridone nucleobases, which are able to bind Cu inside the DNA duplex. Five consecutive copper-hydroxypyridone base pairs were incorporated into a double strand, which were flanked by only one natural nucleobase on both ends. EPR data showed that the distance between copper centers was estimated to be 3.7 ± 0.1 Å, while a natural B-type DNA duplex is only slightly larger (3.4 Å). The appeal for stacking metal ions inside a DNA duplex is the hope to obtain nanoscopic self-assembling metal wires, though this has not been realized yet. | 1 | Gene expression + Signal Transduction |
With the 2006 adoption of the Restriction of Hazardous Substances Directive (RoHS) regulations in the European Union, California banning most uses of lead, and similar regulations elsewhere, the problem of tin pest has returned, since some manufacturers which previously used tin/lead alloys now use predominately tin-based alloys. For example, the leads of some electrical and electronic components are plated with pure tin. In cold environments, this can change to α-modification grey tin, which is not electrically conductive, and falls off the leads. After reheating, it changes back to β-modification white tin, which is electrically conductive. This cycle can cause electrical short circuits and failure of equipment. Such problems can be intermittent as the powdered particles of tin move around. Tin pest can be avoided by alloying with small amounts of electropositive metals or semimetals soluble in tin's solid phase, e.g. antimony or bismuth, which prevent the phase change. | 0 | Metallurgy |
RNA interference (also called "RNA-mediated interference", abbreviated RNAi) is a mechanism for RNA-guided regulation of gene expression in which double-stranded ribonucleic acid inhibits the expression of genes with complementary nucleotide sequences. | 1 | Gene expression + Signal Transduction |
There was no fundamental change in the technology of iron production in Europe for many centuries. European metal workers continued to produce iron in bloomeries. However, the Medieval period brought two developments—the use of water power in the bloomery process in various places (outlined above), and the first European production in cast iron. | 0 | Metallurgy |
Solid-state physics is the study of rigid matter, or solids, through methods such as solid-state chemistry, quantum mechanics, crystallography, electromagnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state physics studies how the large-scale properties of solid materials result from their atomic-scale properties. Thus, solid-state physics forms a theoretical basis of materials science. Along with solid-state chemistry, it also has direct applications in the technology of transistors and semiconductors. | 0 | Metallurgy |
Physical metallurgy is one of the two main branches of the scientific approach to metallurgy, which considers in a systematic way the physical properties of metals and alloys. It is basically the fundamentals and applications of the theory of phase transformations in metal and alloys, as the title of classic, challenging monograph on the subject with this title [http://www.sciencedirect.com/science/book/9780080440194 ]. While chemical metallurgy involves the domain of reduction/oxidation of metals, physical metallurgy deals mainly with mechanical and magnetic/electric/thermal properties of metals – treated by the discipline of solid state physics. Calphad methodology, able to produce Phase diagrams which is the basis for evaluating or estimating physical properties of metals, relies on Computational thermodynamics i.e. on Chemical thermodynamics and could be considered a common and useful field for both the two sub-disciplines. | 0 | Metallurgy |
Receptors on the opposite side of the synaptic gap bind neurotransmitter molecules. Receptors can respond in either of two general ways. First, the receptors may directly open ligand-gated ion channels in the postsynaptic cell membrane, causing ions to enter or exit the cell and changing the local transmembrane potential. The resulting change in voltage is called a postsynaptic potential. In general, the result is excitatory in the case of depolarizing currents, and inhibitory in the case of hyperpolarizing currents. Whether a synapse is excitatory or inhibitory depends on what type(s) of ion channel conduct the postsynaptic current(s), which in turn is a function of the type of receptors and neurotransmitter employed at the synapse. The second way a receptor can affect membrane potential is by modulating the production of chemical messengers inside the postsynaptic neuron. These second messengers can then amplify the inhibitory or excitatory response to neurotransmitters. | 1 | Gene expression + Signal Transduction |
Several X-ray crystallographic and electron cryomicroscopic (cryo-EM) structures of IPRs from mouse, rat, and human have defined the overall architecture of the channel. The 1.2 MDa C4-symmetric assembly consists of an ER-embedded transmembrane domain (TMD) in a domain-swapped 6 transmembrane (6TM) cation channel fold that is capped by a large cytosolic domain (CD). In this manner, IPRs share significant homology with the much larger and distantly-related RyRs. The CD contains all known ligand binding sites, including the IP binding site, two Ca binding sites, an adenine nucleotide binding site, and a CH Zn finger fold. A comprehensive Ca-dependent conformational landscape has recently been defined by cryo-EM. | 1 | Gene expression + Signal Transduction |
For more details on this topic, see flow cytometry
Since the optical identity of each microsphere is known, the quantification of target samples hybridized to the microspheres can be achieved by comparing the relative intensity of target markers in one set of microspheres to target markers in another set of microspheres using flow cytometry. Microspheres can be sorted based using both their unique optical properties and level of hybridization to the target sequence. | 1 | Gene expression + Signal Transduction |
Antitermination is the prokaryotic cell's aid to fix premature termination of RNA synthesis during the transcription of RNA. It occurs when the RNA polymerase ignores the termination signal and continues elongating its transcript until a second signal is reached. Antitermination provides a mechanism whereby one or more genes at the end of an operon can be switched either on or off, depending on the polymerase either recognizing or not recognizing the termination signal.
Antitermination is used by some phages to regulate progression from one stage of gene expression to the next. The lambda gene N, codes for an antitermination protein (pN) that is necessary to allow RNA polymerase to read through the terminators located at the ends of the immediate early genes. Another antitermination protein, pQ, is required later in phage infection. pN and pQ act on RNA polymerase as it passes specific sites. These sites are located at different relative positions in their respective transcription units. | 1 | Gene expression + Signal Transduction |
The untranslated region is seen in prokaryotes and eukaryotes, although the length and composition may vary. In prokaryotes, the 5 UTR is typically between 3 and 10 nucleotides long. In eukaryotes, the 5 UTR can be hundreds to thousands of nucleotides long. This is consistent with the higher complexity of the genomes of eukaryotes compared to prokaryotes. The 3 UTR varies in length as well. The poly-A tail is essential for keeping the mRNA from being degraded. Although there is variation in lengths of both the 5 and 3 UTR, it has been seen that the 5 UTR length is more highly conserved in evolution than the 3' UTR length. | 1 | Gene expression + Signal Transduction |
Several techniques of re-utilising the spoil tips exist, usually including either geotechnics or recycling. Most commonly, old spoil tips are partially revegetated to provide valuable green spaces since they are inappropriate for building purposes. At Nœux-les-Mines, an artificial ski slope has been constructed on the tip. If spoil tips are considered to contain sufficient amounts of residual material, various methods are employed to remove the spoil from the site for subsequent processing.
The oldest coal-based spoil tips may still contain enough coal to begin spontaneous slow combustion. This results in a form of vitrification of the shale, which then acquires sufficient mechanical strength to be of use in road construction. Some can therefore have a new life in being thus exploited; for example, the flattened pile of residue from the 11/19 site of Loos-en-Gohelle. Conversely, others are painstakingly preserved on account of their ecological wealth. With the passage of time, they become colonised with a variety of flora and fauna, sometimes foreign to the region. This diversity follows the mining exploitation. In South Wales some spoil tips are protected as Sites of Special Scientific Interest because they provide a unique habitat for 57 species of Lichen, several of which are at risk due to their limited environment being developed and by vegetation development.
For example, because the miners threw their apple or pear cores into the wagons, the spoil tips became colonised with fruit trees. One can even observe the proliferation of buckler-leaved sorrel (French sorrel – Rumex scutatus), the seeds of which have been carried within the cracks in the pine timber used in the mines. Furthermore, on account of its dark colour, the south face of the spoil tip is significantly warmer than its surroundings, which contributes to the diverse ecology of the area. In this way, the spoil tip of Pinchonvalles, at Avion, hosts 522 different varieties of higher plants. Some sixty species of birds nest there.
Some are used to cultivate vines, as in the case of Spoil Tip No. 7 of the coal-mining region of Mariemont-Bascoup near Chapelle-lez-Herlaimont (province of Hainaut). It produces some 3,000 litres of wine each year from a vineyard on its slopes.
Some spoil tips are used for various sporting activities. The slopes of the spoil tips of 11/19 at Loos-en-Gohelle, or again, at Nœux-les-Mines, are used for winter sports, for example ski and luge. A piste was built on the flank of the heap. In Belgium, a long distance footpath along the spoil tips (GR-412, Sentier des terrils) was opened in 2005. It leads from Bernissart in western Hainaut to Blegny in the province of Liège.
In the United States, coal mining companies have not been allowed to leave behind abandoned piles since the Surface Mining Control and Reclamation Act was passed in 1977. The Virginia City Hybrid Energy Center uses coal gob as a fuel source for energy production. | 0 | Metallurgy |
The lac operon in the prokaryote E. coli consists of genes that produce enzymes to break down lactose. Its operon is an example of a prokaryotic silencer. The three functional genes in this operon are lacZ, lacY, and lacA. The repressor gene, lacI, will produce the repressor protein LacI which is under allosteric regulation. These genes are activated by the presence of lactose in the cell which acts as an effector molecule that binds to LacI. When the repressor is bound to lactose, it will not bind to the operator, which allows RNA polymerase to bind to the promoter to initiate transcription of the operon. When the repressors allosteric site is not bound to lactose, its active site will bind to the operator to prevent RNA polymerase from transcribing the genes of the lac' operon. | 1 | Gene expression + Signal Transduction |
The RegCreative jamboree was stimulated by a community initiative to curate in perpetuity the genomic sequences which have been experimentally determined to control gene expression. This objective is of fundamental importance to evolutionary analysis and translational research as regulatory mechanisms are widely implicated in species-specific adaptation and the etiology of disease. This initiative culminated in the formation of an international consortium of like-minded scientists dedicated to accomplishing this task. The RegCreative jamboree was the first opportunity for these groups to meet to be able to accurately assess the current state of knowledge in gene regulation and to begin to develop standards by which to curate regulatory information.
In total, 44 researchers attended the workshop from 9 different countries and 23 institutions. Funding was also obtained from ENFIN, the BioSapiens Network, FWO Research Foundation, Genome Canada and Genome British Columbia.
The specific outcomes of the RegCreative meeting to date are:
* Prior to the RegCreative Jamboree, attendees were asked to participate in an interannotator agreement assessment. Two ORegAnno mirrors were established with identical sets of publications to be annotated in their queue. In total, 33 redundant annotations from 18 publications were collected. (79 annotations for 31 papers and 60 annotations for 21 papers were collected on servers 1 and 2, respectively.) This effort was used as a baseline from which to establish annotator efficiency.
* Hands-on annotation activities occurred during the first 2 days of the 3-day workshop. In total, 39 researchers contributed 184 TFBS and 317 Regulatory Regions from 96 papers. Many of these researchers were also trained on the ORegAnno system, significantly increasing its experienced-user community. The contribution of these annotations to individual species was 339 annotations in Homo sapiens, 42 annotations in Mus musculus, 72 annotations in Drosophila melanogaster, 24 annotations in Ciona intestinalis, 14 annotations in Rattus norvegicus, 6 annotations in Halocynthia roretzi, 2 annotations in Ciona savignyi and 2 annotations in HIV. Within these annotations, one new dataset was added to ORegAnno; 274 human enhancers were programmatically annotated by Maximillian Haessler, Institute Alfred Fessard, from Visel et al., Nucleic Acids Research, 2006. In total, 130 scientific studies were examined in depth. The annotated papers were pre-selected from expert-curated publications in the ORegAnno queue that had full-text available through HighWire Press.
* There exists an immediate need for improved data standardization and development of associated ontologies. Specifically, this should include the open access development and integration of transcription factor naming conventions and sequence, cell type, cell line, tissue, and evidence ontologies. The groundwork for addressing and prioritizing these needs was accomplished in several ways during the meeting:
** Transcription factor naming issues were addressed through discussion of integration of transcription factor prediction pipelines, such as DBD or flyTF, which have been supplemented with manual curation versus solely manual curated implementations like TFcat.
** [http://www.ccr.buffalo.edu/halfon Marc Halfon], University at Buffalo, led a breakout session to improve the [http://song.sourceforge.net/ Sequence Ontology] from existing ORegAnno and REDfly database conventions within the framework being developed as part of the Open Biomedical Ontologies. A preliminary version of these improvements can be found on the [http://www.bcgsc.ca/wiki/display/oreganno/SeqOntology ORegAnno wiki].
** Learning-based ontology development was widely regarded as an essential feature of the annotation process. Such that, annotators are not restricted from annotating based on the limitations of the controlled vocabulary and that these exceptions can be used to further develop the backbone ontologies.
** Ontology development should be decentralized from the ORegAnno annotation framework. Specifically, it is planned that the ORegAnno evidence ontology will be removed and made available to broader community development.
** Renewed focus on integrating species-specific resources with annotation framework.
* A specific focus of the workshop was addressing the role of text mining in facilitating regulatory annotation. Sessions were led by Dr. Lynette Hirschman, MITRE, and Dr. Martin Krallinger, CNIO, to formulate where text-mining can help. A short term object of text-mining based analyses was formulated around both populating the ORegAnno queue and using the expert-curated portion of the ORegAnno queue to validate text-mining-based publication acquisition. The latter objectives are being led by Dr. Stein Aerts, University of Leuven. | 1 | Gene expression + Signal Transduction |
During the thirteenth century, Mosul, Iraq became home to a school of luxury metalwork which rose to international renown. Artifacts classified as Mosul are some of the most intricately designed and revered pieces of the Middle Ages. | 0 | Metallurgy |
Loss of SFRP1 protein expression is associated with poor overall survival (OS) in patients with early breast cancer (pT1 tumours); this indicates that SFRP1 may be a putative tumor suppressor gene. SFRP1 methylation has been shown to be an independent risk factor for OS. Veeck and colleagues demonstrate, via Kaplan-Meier analysis, that clear SFRP1 promoter methylation is associated with unfavourable prognosis. Furthermore, a correlation between SFRP1 methylation and OS in breast cancer is dependent on a gene dose effect. In order for the OS to be affected, a sufficient amount of tumour cells may be required to lose SFRP1 expression due to promoter methylation. | 1 | Gene expression + Signal Transduction |
The first signaling scaffold protein discovered was the Ste5 protein from the yeast Saccharomyces cerevisiae. Three distinct domains of Ste5 were shown to associate with the protein kinases Ste11, Ste7, and Fus3 to form a multikinase complex. | 1 | Gene expression + Signal Transduction |
The exact purity of very fine precious metals such as platinum, gold and silver can be of great interest. Based on the system of millesimal fineness, a metal is said to be one nine or one nine fine if it is 900 fine, or 90% pure. A metal that is 990 fine is then described as two nines fine and one that is 999 fine is described as three nines fine. Thus, nines are a logarithmic scale of purity for very fine precious metals. Similarly, percentages ending in a 5 have conventional names, traditionally the number of nines, then "five", so 999.5 fine (99.95% pure) is "three nines five", abbreviated 3N5.
Canada's Big Maple Leaf, a coin made of gold at 5N (99.999%) purity, stands as the purest gold coin ever minted, anywhere. The purest gold ever achieved was reportedly produced at the Perth Mint in 1957, at "almost six nines" (99.9999%) purity, as measured by the Worshipful Company of Goldsmiths of London. | 0 | Metallurgy |
Developmental processes provide an example of how changes in synexpression control networks could significantly affect an organism's capacity to evolve and adapt effectively. In animals, it is often beneficial for appendages to co-evolve, and it has been observed that fore-and hind-limbs share expression of Hox genes early in metazoan development. Thus, changes in the regulatory patterns of these genes would affect the development of both the fore- and hind-limbs, facilitating co-evolution. | 1 | Gene expression + Signal Transduction |
Cleavage stimulatory factor or cleavage stimulation factor (CstF or CStF) is a heterotrimeric protein, made up of the proteins CSTF1 (55kDa), CSTF2 (64kDa) and CSTF3 (77kDa), totalling about 200 kDa. It is involved in the cleavage of the 3 signaling region from a newly synthesized pre-messenger RNA (mRNA) molecule. CstF is recruited by cleavage and polyadenylation specificity factor (CPSF) and assembles into a protein complex on the 3 end to promote the synthesis of a functional polyadenine tail, which results in a mature mRNA molecule ready to be exported from the cell nucleus to the cytosol for translation.
The amount of CstF in a cell is dependent on the phase of the cell cycle, increasing significantly during the transition from G0 phase to S phase in mouse fibroblast and human splenic B cells. | 1 | Gene expression + Signal Transduction |
Alfred G. Gilman and Martin Rodbell received the 1994 Nobel Prize in Medicine and Physiology for the discovery of the G Protein System. | 1 | Gene expression + Signal Transduction |
Transcription-translation coupling is a mechanism of gene expression regulation in which synthesis of an mRNA (transcription) is affected by its concurrent decoding (translation). In prokaryotes, mRNAs are translated while they are transcribed. This allows communication between RNA polymerase, the multisubunit enzyme that catalyzes transcription, and the ribosome, which catalyzes translation. Coupling involves both direct physical interactions between RNA polymerase and the ribosome ("expressome" complexes), as well as ribosome-induced changes to the structure and accessibility of the intervening mRNA that affect transcription ("attenuation" and "polarity"). | 1 | Gene expression + Signal Transduction |
The Merv Oasis had been extensively explored in 1904 by an American team; however, the reports published were of a preliminary nature. During the period 1940–50, the Asian Republics started establishing archaeological institutions in their respective countries. Among them, the South Turkmenistan Complex Archaeological Expedition was established in 1946 by Masson under the aegis of the Turkmenistan Academy of Sciences to carry out explorations at several locations. These explorations included:
* 1947-1952: exploration by Alexey Okladnikov of mesolithic sites
* 1940s and 1950s: Eneolithic and Bronze Age excavations by Boris Kuftin
* 1955-62: excavations by V.M. Masson, I.N. Khlopin, and Viktor Sarianidi of neolithic sites at many locations, including Jietun at the Geoksur Oasis
* Since 1965: Bronze Age excavations by Masson covering, among others, the site at Altyndepe
* Excavations by G. N. Lisitsyna to investigate the prehistoric economies and irrigation systems.
* 1977-92: explorations by Khlopin in the Sumbar Valley
Since 1992, excavations have been carried out by a joint project titled “Turkmen-British-Merv Project”. This has yielded historical data on fortifications and a residential complex of the Hellenistic, Parthina and Sassanian period. | 0 | Metallurgy |
* Magnesium aluminide, MgAl
* Titanium aluminide, TiAl
* Iron aluminides, including FeAl and FeAl
* Nickel aluminide, NiAl
See category for a list. | 0 | Metallurgy |
Tailings are also called mine dumps, culm dumps, slimes, refuse, leach residue, slickens, or terra-cone (terrikon). | 0 | Metallurgy |
Like the other members in the CMTM protein family, CMTM6 has a structure that contains domains (i.e. parts) similar to those in chemokine proteins; tetraspanin proteins (also termed transmembrane-4 superfamily proteins); the myelin and lymphocyte protein (also termed MAR protein); proteins that direct membrane vesicle trafficking; and proteins that are embedded across cell membranes. CMTM6 proteins are expressed in virtually all tissues and are located in cell plasma membranes (i.e. cell surface membranes), lysosomes, endosomes, cytosol, attached to the cell's cytoskeleton, and in extracellular spaces. | 1 | Gene expression + Signal Transduction |
Since the introduction of pertussis vaccines in the 1940s and 1950s, different genetic changes have been described surrounding the pertussis toxin. | 1 | Gene expression + Signal Transduction |
This phenomenon describes damage to the metal (nearly always iron or steel) at low temperature by diffusible hydrogen.
Hydrogen can embrittle a number of metals and steel is one of them. It tends to happen to harder and higher tensile steels. Hydrogen cam also embrittle aluminum at high temperatures.). Titanium metal and alloys are also susceptible. | 0 | Metallurgy |
, there are two different theories on the information processing that occurs on enhancers:
* Enhanceosomes – rely on highly cooperative, coordinated action and can be disabled by single point mutations that move or remove the binding sites of individual proteins.
* Flexible billboards – less integrative, multiple proteins independently regulate gene expression and their sum is read in by the basal transcriptional machinery. | 1 | Gene expression + Signal Transduction |
Antisense oligonucleotides (ASOs) are single-stranded DNA molecules with full complementarity to one select target mRNA and may act by blocking protein translation (via steric hindrance), causing mRNA degradation (via RNase H-cleavage) or changing pre-mRNA splicing. These short oligonucleotides have already been approved by the FDA for ten genetic disorders and many are currently in the pipeline to be approved/tested. Using oligonucleotide technology, we are now able to control protein expression via RNA interference, and are able to affect previously defined “undruggable” proteins. Even though this therapy has a lot of promise and potential, it comes with many limitations.
Compared to siRNA and microRNA, ASOs are more versatile in reducing protein expression, they have the ability to also enhance target translation. ASOs can also be customized with ease and accuracy, allowing for the targeting of virtually any mutated gene. This allows for a greater level of application in the field of precision and personalized medicine.
The main challenge of ASO therapies to specific tissues and cellular uptake is what poses a great challenge and limitation. Liposomal delivery is one such way to overcome such issues. Liposomal delivery system comes with its own share of limitations. Serum proteins in the bloodstream destabilize the lipoprotein. This destabilization leads to the depletion of protein and exposing cargo to the unstable environment. This hindrance can be overcome by using PEGs (poly(ethylene glycol) . However, PEGs are not biodegradable causing them to accumulate within the body leading to adverse effects and causing hypersensitivity. In addition, multiple rounds of therapy with PEGs can lead to the formation of PEG antibodies, which can lead to lack of efficiency in preventing the rupture of the liposome that it is attached to.
Using immunoliposomes it has been shown that targeting can be more specific as by using antibody’s specific to the protein of expression in that area, it results in the ASO drug directly impact the target site and nowhere else. Moreover, immunoliposomes are slow to dissociate leading to precise release of the ASO drug which they encapsulate. | 1 | Gene expression + Signal Transduction |
Nervana is an investigational V construct that knocks down the expression of protein kinase C gamma (PKCγ) known to be associated with neuropathic pain and morphine tolerance.
Two conserved PKCγ sequences across all key model species and humans have been identified, and both single and double DNA cassettes are designed. In vitro, the expression of PKCγ was silenced by 80%. When similar DDRNAI constructs were delivered intrathecally using a lentiviral vector, pain relief in a neuropathic-rat model was demonstrated. | 1 | Gene expression + Signal Transduction |
Tank and vat leaching involves placing ore, usually after size reduction and classification, into large tanks or vats at ambient operating conditions containing a leaching solution and allowing the valuable material to leach from the ore into solution.
In tank leaching the ground, classified solids are already mixed with water to form a slurry or pulp, and this is pumped into the tanks. Leaching reagents are added to the tanks to achieve the leaching reaction. In a continuous system the slurry will then either overflow from one tank to the next, or be pumped to the next tank. Ultimately the “pregnant” solution is separated from the slurry using some form of liquid/solid separation process, and the solution passes on to the next phase of recovery.
In vat leaching the solids are loaded into the vat, once full the vat is flooded with a leaching solution. The solution drains from the tank, and is either recycled back into the vat or is pumped to the next step of the recovery process.
. Vat leach units are rectangular containers (drums, barrels, tanks or vats), usually very big and made of wood or concrete, lined with material resistant to the leaching media. The treated ore is usually coarse.
The vats are usually run sequentially to maximize the contact time between the ore and the reagent. In such a series the leachate collected from one container is added to another vat with fresher ore
As mentioned previously tanks are equipped with agitators to keep the solids in suspension in the vats and improve the solid to liquid to gas contact. Agitation is further assisted by the use of tank baffles to increase the efficiency of agitation and prevent centrifuging of slurries in circular tanks... | 0 | Metallurgy |
Metallurgists throughout medieval Europe were generally free to move within different regions. For instance, German metallurgists in search of rich precious metal ores took the lead in mining and influenced the course of metal production, not only in East and South Germany but also in almost all of Central Europe and the Eastern Alps.
As mining gradually became a task for specialized craftsmen, miners moved in large groups and formed settlements close to mines, each with their own customs. They were always welcomed by regional authorities, as the latter were interested in increasing revenue through the profitable exploitation of the mineral-rich subsurface. These authorities claimed a portion of the output, and smiths and miners were provided with land for cottages, mills, forges, farming, and pasture, while also being allowed to utilize streams and lumber. (Nef 1987, 706–715).
Advancing into the high and late Middle Ages, a notable shift occurred where smelting sites gained geographical independence from mines, leading to the separation of metalworking from ore smelting. The urban expansion that unfolded from the 10th century onwards, coupled with the pivotal influence of towns, afforded metallurgists an optimal setting to cultivate and refine their technological advancements. This era witnessed the systematic formation of metallurgical guilds, with their workshops often converging on the outskirts of these urban centers. (McLees 1996).
In medieval societies, liberal and mechanical arts were considered to be totally different disciplines. Metallurgists, like all craftsmen and artisans, almost always lacked the formal education that would inform a methodical intellectual background. Instead, they were the pioneers of causal thinking based on empirical observation and experimentation (Zilsel 2000). | 0 | Metallurgy |
In metazoans, in order to respond to environmental stress, differentiate properly, and progress normally through the cell cycle, a eukaryotic cell needs a specific and coordinated gene expression program, which involves the highly regulated transcription of thousands of genes. This gene regulation is in large part controlled, in a tissue-specific manner, by the binding of transcription factors to noncoding genomic regions referred to as cis-regulatory modules (CRMs), activating or repressing gene expression by modulating the structure of the chromatin and therefore having a positive or negative effect on transcription regulation. CRMs activating gene expression are often referred to as transcriptional enhancers, whereas those repressing gene expression are referred to as transcriptional silencers. | 1 | Gene expression + Signal Transduction |
In 1681, Samuel Pepys (then serving as Admiralty Secretary) agreed to the removal of lead sheathing from English Royal Navy vessels to prevent the mysterious disintegration of their rudder-irons and bolt-heads, though he confessed himself baffled as to the reason the lead caused the corrosion.
The problem recurred when vessels were sheathed in copper to reduce marine weed accumulation and protect against shipworm. In an experiment, the Royal Navy in 1761 had tried fitting the hull of the frigate HMS Alarm with 12-ounce copper plating. Upon her return from a voyage to the West Indies, it was found that although the copper remained in fine condition and had indeed deterred shipworm, it had also become detached from the wooden hull in many places because the iron nails used during its installation "were found dissolved into a kind of rusty Paste". To the surprise of the inspection teams, however, some of the iron nails were virtually undamaged. Closer inspection revealed that water-resistant brown paper trapped under the nail head had inadvertently protected some of the nails: "Where this covering was perfect, the Iron was preserved from Injury". The copper sheathing had been delivered to the dockyard wrapped in the paper which was not always removed before the sheets were nailed to the hull. The conclusion therefore reported to the Admiralty in 1763 was that iron should not be allowed direct contact with copper in sea water. | 0 | Metallurgy |
High-frequency vibrating screening equipment is a shaker whose frame is fixed and the drive vibrates only the screen cloth. High frequency vibration equipment is for particles that are in this particle size range of an 1/8 in (3 mm) down to a +150 mesh. Traditional shaker screeners have a difficult time making separations at sizes like 44 microns. At the same time, other high energy sieves like the Elcan Industries' advanced screening technology allow for much finer separations down to as fine as 10um and 5um, respectively.
These shakers usually make a secondary cut for further processing or make a finished product cut.
These shakers are usually set at a steep angle relative to the horizontal level plane. Angles range from 25 to 45 degrees relative to the horizontal level plane. | 0 | Metallurgy |
In cancers, loss of expression of genes occurs about 10 times more frequently by hypermethylation of promoter CpG islands than by mutations. For instance, in colon tumors compared to adjacent normal-appearing colonic mucosa, about 600 to 800 heavily methylated CpG islands occur in promoters of genes in the tumors while these CpG islands are not methylated in the adjacent mucosa. In contrast, as Vogelstein et al. point out, in a colorectal cancer there are typically only about 3 to 6 driver mutations and 33 to 66 hitchhiker or passenger mutations. | 1 | Gene expression + Signal Transduction |
In materials where the maximum applied-stress-intensity factor exceeds the stress-corrosion cracking-threshold value, stress corrosion adds to crack-growth velocity. This is shown in the schematic on the right. In a corrosive environment, the crack grows due to cyclic loading at a lower stress-intensity range; above the threshold stress intensity for stress corrosion cracking, additional crack growth (the red line) occurs due to SCC. The lower stress-intensity regions are not affected, and the threshold stress-intensity range for fatigue-crack propagation is unchanged in the corrosive environment. In the most-general case, corrosion-fatigue crack growth may exhibit both of the above effects; crack-growth behavior is represented in the schematic on the left. | 0 | Metallurgy |
AREs are recognized by RNA binding proteins such as tristetraprolin (TTP), AUF1, and Hu Antigen R (HuR). Although the exact mechanism is not very well understood, recent publications have attempted to propose the action of some of these proteins. AUF1, also known as hnRNP D, binds AREs through RNA recognition motifs (RRMs). AUF1 is also known to interact with the translation initiation factor eIF4G and with poly(A)-binding protein, indicating that AUF1 senses the translational status of mRNA and decays accordingly through the excision of the poly(A) tail.
TTP's expression is rapidly induced by insulin. Immunoprecipitation experiments have shown that TTP co-precipitates with an exosome, suggesting that it helps recruit exosomes to the mRNA containing AREs. Alternatively, HuR proteins have a stabilizing effect—their binding to AREs increases the half-life of mRNAs. Similar to other RNA-binding proteins, this class of proteins contain three RRMs, two of which are specific to ARE elements. A likely mechanism for HuR action relies on the idea that these proteins compete with other proteins that normally have a destabilizing effect on mRNAs. HuRs are involved in genotoxic response—they accumulate in the cytoplasm in response to UV exposure and stabilize mRNAs that encode proteins involved in DNA repair. | 1 | Gene expression + Signal Transduction |
* Expert Guide: Materialography/Metallography, QATM Academy, ATM Qness GmbH, 2022.
* Metallographic Preparation of Ceramic and Cermet Materials, [https://web.archive.org/web/20101007084342/http://leco.com/resources/met_tips/met_tip19.pdf Leco Met-Tips No. 19], 2008.
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* Structure, Volume 33, [https://web.archive.org/web/20071203130459/http://www.struers.com/default.asp?top_id=5&main_id=43&doc_id=307&target=_self Struers A/S], 1998, p 3–20.
* [http://www.struers.com/default.asp?top_id=5&main_id=19&sub_id=25&doc_id=89 Struers Metalog Guide]
* S. Binkowski, R. Paul & M. Woydt, "Comparing Preparation Techniques Using Microstructural Images of Ceramic Materials," Structure, Vol 39, 2002, p 8–19.
* R.E. Chinn, Ceramography, ASM International and the American Ceramic Society, 2002, .
* D.J. Clinton, A Guide to Polishing and Etching of Technical and Engineering Ceramics, The Institute of Ceramics, 1987.
* [http://www.udri.udayton.edu/DLCM/Home.asp/ Digital Library of Ceramic Microstructures], University of Dayton, 2003.
* G. Elssner, H. Hoven, G. Kiessler & P. Wellner, translated by R. Wert, Ceramics and Ceramic Composites: Materialographic Preparation, Elsevier Science Inc., 1999, .
* R.M. Fulrath & J.A. Pask, ed., Ceramic Microstructures: Their Analysis, Significance, and Production, Robert E. Krieger Publishing Co., 1968, .
* K. Geels in collaboration with D.B. Fowler, W-U Kopp & M. Rückert, Metallographic and Materialographic Specimen Preparation, Light Microscopy, Image Analysis and Hardness Testing, ASTM International, 2007, .
* H. Insley & V.D. Fréchette, Microscopy of Ceramics and Cements, Academic Press Inc., 1955.
* W.E. Lee and W.M. Rainforth, Ceramic Microstructures: Property Control by Processing, Chapman & Hall, 1994.
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* H. Mörtel, "Microstructural Analysis," Engineered Materials Handbook, Volume 4: Ceramics and Glasses, ASM International, 1991, p 570–579, .
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* D.C. Zipperian, Metallographic Handbook, PACE Technologies, 2011. | 0 | Metallurgy |
Melt spinning is used to manufacture thin metal sheets or ribbons that are near amorphous or non-crystalline. The unique resulting electric and magnetic properties of melt-spun metals are a consequence of this structure as well as the composition of the alloy or metal that was used to form the ribbon. | 0 | Metallurgy |
In corrosion, spalling occurs when a substance (metal or concrete) sheds tiny particles of corrosion products as the corrosion reaction progresses. Although they are not soluble or permeable, these corrosion products do not adhere to the parent material's surface to form a barrier to further corrosion, as happens in passivation. Spallation happens as the result of a large volume change during the reaction.
In the case of actinide metals (most notably the depleted uranium used in some types of ammunition), the material expands so strongly upon exposure to air that a fine layer of oxide is forcibly expelled from the surface. A slowly oxidised plug of metallic uranium can sometimes resemble an onion subjected to desquamation. The main hazard however arises from the pyrophoric character of actinide metals which can spontaneously ignite when their specific area is high. This property, along with the inherent toxicity and (for some to a lesser extent) radioactivity of these elements, make them dangerous to handle in metallic form under air. Therefore, they are often handled under an inert atmosphere (nitrogen or argon) inside an anaerobic glovebox. | 0 | Metallurgy |
*ACVR1 NM_001105 similar to ACVRL1 TGF Beta receptor family Rendu-Osler-Weber syndrome
*ACVR1B NM_004302
*CD23 FCER2 low affinity IgE receptor (lectin) | 1 | Gene expression + Signal Transduction |
The theory that metallurgy was imported into Europe from the Near East has been practically ruled out. A second hypothesis, that there were two main points of origin of metallurgy in Europe, in southern Spain and in West Bulgaria, is also doubtful due to the existence of sites outside the centers of diffusion where metallurgy was known simultaneously with, or before, those in the ‘original’ nuclei, such as Brixlegg (Tyrol, Austria), while sites closer to the supposed origins of metallurgy, such as in the north of Spain, show fewer metal artifacts than sites in the south and practically no evidence of production.
Currently, the general opinion is that the development of metallurgy took place independently in different places, at different times, with various techniques. One fact that supports this interpretation is that, although the final products (beads, rings, sickles, swords, axes, etc.) are quite similar throughout Europe, the method of production is not. Thus the use of crucibles was the technique utilized in the south of Spain, whereas central Europe employed a slagging process, but Cabrierés (France) used a primitive oxidizing non-slagging process, while in the British Isles the absence of debris, slag or ceramic suggests another technique.
Consequently, the way in which metallurgy was initiated differs considerably depending on the region. There are areas in which copper seems to play a crucial role (i.e., the Balkans), whereas other areas show no interest in it at all. Then there are societies that use copper artifacts, but do not practice metallurgy, and there are other ones that fully adopt some of the cultural innovations but ignore the rest. One example of the latter is Basque country in northern Spain, where splendid large dolmens are present along the Ebro river, but metal is rather infrequent, and when it does appear between the trapping, it is more often bronze or arsenical copper than copper. According to radiocarbon dating, the Pre-Bell Beaker Chalcolithic with copper metallurgy began on the Iberian Peninsula in the last third of the IV millennium cal. BC, in the Northern Iberian Plateau in 3000 cal. BC and the Bell Beaker Chalcolithic appeared around 2500 cal. BC. | 0 | Metallurgy |
Smelting has serious effects on the environment, producing wastewater and slag and releasing such toxic metals as copper, silver, iron, cobalt, and selenium into the atmosphere. Smelters also release gaseous sulfur dioxide, contributing to acid rain, which acidifies soil and water.
The smelter in Flin Flon, Canada was one of the largest point sources of mercury in North America in the 20th century. Even after smelter releases were drastically reduced, landscape re-emission continued to be a major regional source of mercury. Lakes will likely receive mercury contamination from the smelter for decades, from both re-emissions returning as rainwater and leaching of metals from the soil. | 0 | Metallurgy |
Alternative polyadenylation (APA) is a regulatory mechanism that forms multiple 3' end on mRNA.
APA isoforms from the same gene can encode different proteins and/or contain different 3' untranslated regions (UTRs). Deregulation of APA has been associated with a number of human diseases. Since longer UTRs have more binding sites for microRNAs and/or RNA-binding proteins in comparison to shorter UTRs, APA require different stability, translation efficiency, and/or intracellular localization.
Mammalian PASs have a number of key cis elements.
* A(A/U)AAA hexamer
* U/GU-rich downstream element (DSE)
* U-rich upstream auxiliary elements (USEs)
* Upstream sequences conforming to the consensus UGUA
PAS sequences are variable, and many PASs lack one or more cis elements. PAS recognition is accomplished by protein-RNA interactions.
CPSF synergistically binds to the AAUAAA hexamer and CstF synergistically binds to the downstream element (DSE). The CFI complex binds to the UGUA motifs. CPSF, CstF, and CFI bind directly to RNA. They also recruit other proteins such as CFII, symplekin, and the poly(A) polymerase (PAP) to assemble the mRNA 3' processing complex, also known as the cleavage and polyadenylation complex. The assembly of these factors are facilitated by the C-terminal domain (CTD) of the RNA polymerase II (RNAP II) large subunit. The CTD provides a landing pad for mRNA processing factors. | 1 | Gene expression + Signal Transduction |
Most LOM observations are conducted using bright-field (BF) illumination, where the image of any flat feature perpendicular to the incident light path is bright, or appears to be white. But, other illumination methods can be used and, in some cases, may provide superior images with greater detail. Dark-field microscopy (DF), is an alternative method of observation that provides high-contrast images and actually greater resolution than bright-field. In dark-field illumination, the light from features perpendicular to the optical axis is blocked and appears dark while the light from features inclined to the surface, which look dark in BF, appear bright, or "self-luminous" in DF. Grain boundaries, for example, are more vivid in DF than BF. | 0 | Metallurgy |
Disrupted functioning of cAMP has been noted as one of the mechanisms of several bacterial exotoxins.
They can be subgrouped into two distinct categories:
* Toxins that interfere with enzymes ADP-ribosyl-transferases, and
* invasive adenylate cyclases. | 1 | Gene expression + Signal Transduction |
Attenuation was first observed by Charles Yanofsky in the trp operon of E. coli. The first observation was linked to two separate scientific facts. Mutations which knocked out the trp R (repressor) gene still showed some regulation of the trp operon (these mutants were not fully induced/repressed by tryptophan). The total range of trp operon regulation is about 700 X (on/off). When the trp repressor was knocked out, one still got about 10 X regulation by the absence or presence of trp. When the sequence of the beginning of the trp operon was determined an unusual open reading frame (ORF) was seen immediately preceding the ORFs for the known structural genes for the tryptophan biosynthetic enzymes. The general structural information shown below was observed from the sequence of the trp operon.
First, Yanofsky observed that the ORF contained two tandem Trp codons and the protein had a Trp percent composition which was about 10X normal. Second, the mRNA in this region contained regions of dyad symmetry which would allow it to form two mutually exclusive secondary structures. One of the structures looked exactly like a rho-independent transcription termination signal. The other secondary structure, if formed, would prevent the formation of this secondary structure and thus the terminator. This other structure is called the "preemptor". | 1 | Gene expression + Signal Transduction |
Signal transduction mediated by the superfamily of GPCRs dates back to the origin of multicellularity. Mammalian-like GPCRs are found in fungi, and have been classified according to the GRAFS classification system based on GPCR fingerprints. Identification of the superfamily members across the eukaryotic domain, and comparison of the family-specific motifs, have shown that the superfamily of GPCRs have a common origin. Characteristic motifs indicate that three of the five GRAFS families, Rhodopsin, Adhesion, and Frizzled, evolved from the Dictyostelium discoideum cAMP receptors before the split of opisthokonts. Later, the Secretin family evolved from the Adhesion GPCR receptor family before the split of nematodes. Insect GPCRs appear to be in their own group and Taste2 is identified as descending from Rhodopsin. Note that the Secretin/Adhesion split is based on presumed function rather than signature, as the classical Class B (7tm_2, ) is used to identify both in the studies. | 1 | Gene expression + Signal Transduction |
In the Late Bronze Age, the site became an administrative center of a larger region in the kingdom of Isuwa. The city was heavily fortified, probably due to the Hittite threat from the west. It was culturally influenced by the Hurrians, Mitanni and the Hittites.
Around 1350 BC, Šuppiluliuma I of the Hittites conquered Melid in his war against Tushratta of Mitanni. At the time Melid was a regional capital of Isuwa at the frontier between the Hittites and the Mitanni; it was loyal to Tushratta. Suppiluliuma I used Melid as a base for his military campaign to sack the Mitanni capital Washukanni. | 0 | Metallurgy |
Phylogenetic footprinting is a technique that utilizes multiple sequence alignments to determine locations of conserved sequences such as regulatory elements. Along with multiple sequence alignments, phylogenetic footprinting also requires statistical rates of conserved and non-conserved sequences. Using the information provided by multiple sequence alignments and statistical rates, one can identify the best conserved motifs in the orthologous regions of interest. | 1 | Gene expression + Signal Transduction |
TaqMan probes consist of a fluorophore covalently attached to the 5’-end of the oligonucleotide probe and a quencher at the 3’-end. Several different fluorophores (e.g. 6-carboxyfluorescein, acronym: FAM, or tetrachlorofluorescein, acronym: TET) and quenchers (e.g. tetramethylrhodamine, acronym: TAMRA) are available. The quencher molecule quenches the fluorescence emitted by the fluorophore when excited by the cycler’s light source via Förster resonance energy transfer (FRET). As long as the fluorophore and the quencher are in proximity, quenching inhibits any fluorescence signals.
TaqMan probes are designed such that they anneal within a DNA region amplified by a specific set of primers. (Unlike the diagram, the probe binds to single stranded DNA.) TaqMan probes can be conjugated to a minor groove binder (MGB) moiety, dihydrocyclopyrroloindole tripeptide (DPI), in order to increase its binding affinity to the target sequence; MGB-conjugated probes have a higher melting temperature (T) due to increased stabilization of van der Waals forces. As the Taq polymerase extends the primer and synthesizes the nascent strand (from the single-stranded template), the 5 to 3 exonuclease activity of the Taq polymerase degrades the probe that has annealed to the template. Degradation of the probe releases the fluorophore from it and breaks the proximity to the quencher, thus relieving the quenching effect and allowing fluorescence of the fluorophore. Hence, fluorescence detected in the quantitative PCR thermal cycler is directly proportional to the fluorophore released and the amount of DNA template present in the PCR. | 1 | Gene expression + Signal Transduction |
In 1931, Peirce, still president of the Baltimore Copper Smelting & Rolling Co., as well as being President of the Peirce-Smith Converter Company and vice president of the American Smelting & Refining Company, is awarded of the James Douglas medal, for "his numerous improvements in devices for smelting, refining, and rolling copper". | 0 | Metallurgy |
Stirred tank, also called agitation leaching, involves contacting material, which has usually undergone size reduction and classification, with leach solution in agitated tanks. The agitation can enhance reaction kinetics by enhancing mass transfer. Tanks are often configured as reactors in series. | 0 | Metallurgy |
In chemistry, sparging, also known as gas flushing in metallurgy, is a technique in which a gas is bubbled through a liquid in order to remove other dissolved gas(es) and/or dissolved volatile liquid(s) from that liquid. It is a method of degassing. According to Henry's law, the concentration of each gas in a liquid is proportional to the partial pressure of that gas (in the gaseous state) in contact with the liquid. Sparging introduces a gas that has little or no partial pressure of the gas(es) to be removed, and increases the area of the gas-liquid interface, which encourages some of the dissolved gas(es) to diffuse into the sparging gas before the sparging gas escapes from the liquid. Many sparging processes, such as solvent removal, use air as the sparging gas. To remove oxygen, or for sensitive solutions or reactive molten metals, a chemically inert gas such as nitrogen, argon, or helium is used. | 0 | Metallurgy |
Electroslag remelting (ESR), also known as electro-flux remelting, is a process of remelting and refining steel and other alloys for mission-critical applications in aircraft, thermal power stations, nuclear power plants, military technology and others.
The electroslag remelting (ESR) process is used to remelt and refine steels and various super-alloys, resulting in high-quality ingots. This process can be started up through vacuum induction melting. The ESR process uses the as-cast alloy as a consumable electrode. Electric current (generally AC) is passed between the electrode and the new ingot, which is formed in the bottom of a water-cooled copper mold. The new ingot is covered in an engineered slag that is superheated by the electric current. The electrode tip is slowly melted from contact with the slag. These metal droplets travel through the slag to the bottom of the water-cooled mold and slowly freeze as the ingot is directionally solidified upwards from the bottom of the mold. The slag pool floats above the refined alloy, continuously floating upwards as the alloy solidifies. The molten metal is cleaned of impurities that chemically react with the slag or otherwise float to the top of the molten pool as the molten droplets pass through the slag.
Electroslag remelting uses highly reactive slags (calcium fluoride, lime, alumina, or other oxides are usually the main components) to reduce the amount of type-A sulfide present in biometal alloys. It is a common practice in European industries. ESR reduces other types of inclusions as well, and is seen as an alternative to the vacuum arc remelting (VAR) method that is prevalent in US industries.
An example of the use of the electro-slag refined (ESR) steel technique is the L30 tank gun.
CrNi60WTi is a stainless steel which is best formed by either electro-slag remelting or vacuum arc remelting. This alloy can be used for the construction of nuclear power plants. | 0 | Metallurgy |
There are three main G-protein-mediated signaling pathways, mediated by four sub-classes of G-proteins distinguished from each other by sequence homology (G, G, G, and G). Each sub-class of G-protein consists of multiple proteins, each the product of multiple genes or splice variations that may imbue them with differences ranging from subtle to distinct with regard to signaling properties, but in general they appear reasonably grouped into four classes. Because the signal transducing properties of the various possible βγ combinations do not appear to radically differ from one another, these classes are defined according to the isoform of their α-subunit.
While most GPCRs are capable of activating more than one Gα-subtype, they also show a preference for one subtype over another. When the subtype activated depends on the ligand that is bound to the GPCR, this is called functional selectivity (also known as agonist-directed trafficking, or conformation-specific agonism). However, the binding of any single particular agonist may also initiate activation of multiple different G-proteins, as it may be capable of stabilizing more than one conformation of the GPCRs GEF domain, even over the course of a single interaction. In addition, a conformation that preferably activates one isoform of Gα may activate another if the preferred is less available. Furthermore, feedback pathways may result in receptor modifications (e.g., phosphorylation) that alter the G-protein preference. Regardless of these various nuances, the GPCRs preferred coupling partner is usually defined according to the G-protein most obviously activated by the endogenous ligand under most physiological or experimental conditions. | 1 | Gene expression + Signal Transduction |
Plants contain CaM-related proteins (CMLs) apart from the typical CaM proteins. The CMLs have about 15% amino acid similarity with the typical CaMs. Arabidopsis thaliana contains about 50 different CML genes which leads to the question of what purpose these diverse ranges of proteins serve in the cellular function. All plant species exhibit this diversity in the CML genes. The different CaMs and CMLs differ in their affinity to bind and activate the CaM-regulated enzymes in vivo. The CaM or CMLs are also found to be located in different organelle compartments. | 1 | Gene expression + Signal Transduction |
Gene regulation by miRNA is widespread across many genomes – by some estimates more than 60% of human protein-coding genes are likely to be regulated by miRNA, though the quality of experimental evidence for miRNA-target interactions is often weak. Because processing by microprocessor is a major determinant of miRNA abundance, microprocessor itself is then an important target of regulation.
Both Drosha and DGCR8 are subject to regulation by post-translational modifications modulating stability, intracellular localization, and activity levels. Activity against particular substrates may be regulated by additional protein cofactors interacting with the microprocessor complex. The loop region of the pri-miRNA stem-loop is also a recognition element for regulatory proteins, which may up- or down-regulate microprocessor processing of the specific miRNAs they target.
Microprocessor itself is auto-regulated by negative feedback through association with a pri-miRNA-like hairpin structure found in the DGCR8 mRNA, which when cleaved reduces DGCR8 expression. The structure in this case is located in an exon and is unlikely to itself function as miRNA in its own right. | 1 | Gene expression + Signal Transduction |
In chemistry, the lever rule is a formula used to determine the mole fraction (x) or the mass fraction (w) of each phase of a binary equilibrium phase diagram. It can be used to determine the fraction of liquid and solid phases for a given binary composition and temperature that is between the liquidus and solidus line.
In an alloy or a mixture with two phases, α and β, which themselves contain two elements, A and B, the lever rule states that the mass fraction of the α phase is
where
* is the mass fraction of element B in the α phase
* is the mass fraction of element B in the β phase
* is the mass fraction of element B in the entire alloy or mixture
all at some fixed temperature or pressure. | 0 | Metallurgy |
The Imd pathway appears to have evolved in the last common ancestor of centipedes and insects. However certain lineages of insects have since lost core components of Imd signalling. The first-discovered and most famous example is the pea aphid Acyrthosiphon pisum. It is thought that plant-feeding aphids have lost Imd signalling as they bear a number of bacterial endosymbionts, including both nutritional symbionts that would be disrupted by aberrant expression of antimicrobial peptides, and defensive symbionts that cover for some of the immune deficiency caused by loss of Imd signalling. It has also been suggested that antimicrobial peptides, the downstream components of Imd signalling, may be detrimental to fitness and lost by insects with exclusively plant-feeding ecologies. | 1 | Gene expression + Signal Transduction |
Signal peptides are usually located at the N-terminus of proteins. Some have C-terminal or internal signal peptides (examples: peroxisomal targeting signal and nuclear localisation signal). The structure of these nonclassical signal peptides differs vastly from the N-terminal signal peptides. | 1 | Gene expression + Signal Transduction |
Modern puddling was one of several processes developed in the second half of the 18th century in Great Britain for producing bar iron from pig iron without the use of charcoal. It gradually replaced the earlier charcoal-fueled process, conducted in a finery forge. | 0 | Metallurgy |
Huntingtons disease (HD) is an inherited neurodegenerative disorder, with symptoms emerging during an individuals mid-adulthood. The most noticeable symptoms of this progressive disease are cognitive and motor impairments, as well as behavioral alterations. These impairments can develop into dementia, chorea, and eventually death. At the molecular level, HD results from a mutation in the huntingtin protein (Htt). More specifically, there is an abnormal repetition of a CAG sequence towards the 5’-end of the gene, which then leads to the development of a toxic polyglutamine (polyQ) stretch in the protein. The mutated Htt protein affects an individual's proper neural functions by inhibiting the action of REST/NRSF.
REST/NRSF is an important silencer element that binds to regulatory regions to control the expression of certain proteins involved in neural functions. The mechanistic actions of huntingtin are still not fully understood, but a correlation between Htt and REST/NRSF exists in HD development. By attaching to the REST/NRSF, the mutated huntingtin protein inhibits the action of the silencer element, and retains it in the cytosol. Thus, REST/NRSF cannot enter the nucleus and bind to the 21 base-pair RE-1/NRSE regulatory element. An adequate repression of specific target genes are of fundamental importance, as many are involved in the proper development of neuronal receptors, neurotransmitters, synaptic vesicle proteins, and channel proteins. A deficiency in the proper development of these proteins can cause the neural dysfunctions seen in Huntingtons disease. In addition to the lack of repression due to the inactive REST/NRSF, mutated huntingtin protein can also decrease the transcription of the brain-derived neurotropic factor (BDNF) gene. BDNF influences the survival and development of neurons in the central nervous system as well as the peripheral nervous system. This abnormal repression occurs when the RE1/NRSE region within the BDNF promoter region is activated by the binding of REST/NRSF, which leads to the lack of transcription of the BDNF gene. Hence, the anomalous repression of the BDNF protein suggests a significant impact in Huntingtons disease. | 1 | Gene expression + Signal Transduction |
c-Src is a gene that codes for proto-oncogene tyrosine-protein kinase Src, a protein important for normal mitotic cycling. It is phosphorylated and dephosphorylated to turn signaling on and off. Proto-oncogene tyrosine-protein kinase Src must be localized to the plasma membrane in order to phosphorylate other downstream targets; myristoylation is responsible for this membrane targeting event. Increased myristoylation of c-Src can lead to enhanced cell proliferation and be responsible for transforming normal cells into cancer cells. Activation of c-Src can lead to the so-called "hallmarks of cancer", among them upregulation of angiogenesis, proliferation, and invasion. | 1 | Gene expression + Signal Transduction |
Initially, copper is oxidized to the cuprous ion:
(1) Cu → Cu + e
The cuprous ion reacts with the chloride ion to form the insoluble white colored salt cuprous chloride:
(2) Cu + Cl → CuCl
The cuprous chloride reacts with atmospheric moisture and oxygen to form a green cupric chloride/cupric hydroxide compound and hydrochloric acid:
(3) 4 CuCl + 4 HO + O → CuCl·3 Cu(OH) + 2 HCl
The remaining copper is oxidised by air to the cuprous ion:
(4) Cu → Cu + e
The cuprous ion reacts with the chloride ion in the hydrochloric acid to form the insoluble white colored salt cuprous chloride:
(5) Cu + Cl → CuCl
The reaction then repeats from equation (3). It is the presence of two different white and green salts that lead to the fuzzy green appearance. | 0 | Metallurgy |
Due to the potential for wear protection at high temperatures beyond which conventional lubricants can be used, possible uses have been speculated in applications such as car engines, power generation and even aerospace, where there is an increasing demand for ever higher efficiency and thus operating temperature. | 0 | Metallurgy |
CKIα or CKIδ is essential in modulating the nuclear export of eukaryotic translation initiation factor 6 (eIF6), a protein with essential nuclear and cytoplasmic roles in biogenesis of the 60S subunit of the eukaryotic ribosome. Phosphorylation of Ser-174 and Ser-175 by CKI promotes nuclear export of eIF6 while dephosphorylation by calcineurin promotes nuclear accumulation of eIF6. It is unclear whether the same mechanism is responsible for eIF6 cycling in yeast and if other kinases also play roles in these processes.
CKI homologs are also implicated in cytoplasmic shuttling of nuclear factor of activated T-cells (NFAT) through observation that the transcription factor Crz1p is phosphorylated by a CKI homolog in yeast. | 1 | Gene expression + Signal Transduction |
Subsets and Splits